Big Sister is Doing Just Fine...
I don't know how three year olds are supposed to respond to new siblings, and if they're not supposed to manage it with grace and sweetness, then Zoey spoiled us to a lifetime of ignorance.
She looks for her sister when she wakes up. She kisses and hugs her. She understands that Mommy is busy, and she doesn't make a fuss. She tells people that she has a new sister.
People ask how Maggie is doing and I say, "fine," and when they ask how Zoey is I always sputter, "finer." It's not a word, I know, but it's fun to say out loud, and besides, legit word or not, she is.
She has her own baby, a doll, and she feeds her, and burps her, and mostly enjoys her company since she never cries. Of course, she's not all tat careful with her baby "Rose,"and sometimes leaves her outside, or drops her. She got a habit of leaving her under the pillows on the couch so that Rose gets' regularly sat on. Thankfully she treats her sister way better.